Voltage Level Detector (CB22135E)

We found this circuit in an English documentation from the 80's. Transistors are general-purpose types.

Multipurpose Alarm (CB17301E)
We found this simple alarm circuit in a 1986 documentation. The circuit uses sensors of the NA...
Sound Operated Switch (CB6315E)
This sound relay or Vox was found in 70s RCA documentation. SCRs can be common types today and...
Beat Oscillator (CB4208E)
Placed near a common receiver, this oscillator is intended to generate a beating signal to receive...